1. Field of the Invention
The present invention relates to an input buffer circuit having a function of canceling an offset voltage.
2. Description of the Background Art
In a conventional input buffer circuit having a composition that plural differential amplifier circuits are in a cascade connection with each other, various circuit elements such as a resistance for a voltage division, a terminating resistance and so on are connected with a data path (or a signal path) to cancel an offset voltage.
Besides, a technique corresponding to a method of canceling the offset voltage is disclosed in Japanese Patent Application Laid-Open Nos. 2002-9561, 2003-8407 and H04-192703 (1992).
However, according to the conventional input buffer circuit, a problem arises that there is a case that a capability of the input buffer circuit drops that a noise increases, a bandwidth of the differential amplifier circuit becomes narrow and so on under the influence of the circuit elements described above which are connected with the data path.
Moreover, a case can arise that the offset voltage cannot be appropriately canceled under the influence of a DC component included in a signal outputted from a circuit of a former stage. Accordingly, a problem arises that a connection type with a circuit of a former stage is limited to a connection type through a capacitor (a capacity coupling type).